1. Field of the Invention
The present invention relates generally to angled tissue cutting instruments including an elongate outer member having a bend and a distal end with a cutting window and, more particularly, to angled tissue cutting instruments in which the cutting window is variably positionable relative to the bend, to indexing tools for variably positioning the cutting windows of angled tissue cutting instruments, and to methods of variably positioning a cutting window of an angled tissue cutting instrument.
2. Brief Discussion of the Related Art
Tissue cutting instruments comprising an elongate outer tubular member and an elongate inner member rotatably disposed in the outer tubular member to cut anatomical tissue have become well-accepted for use in various surgical procedures. Typically, the inner member has a distal end with a cutting edge and the outer member has a distal end with a cutting window through which the cutting edge is exposed to cut anatomical tissue when the inner member is rotated within the outer member. The cutting edge may have various configurations in accordance with the type of tissue and/or the type of cutting action to be accomplished. In some instances, the distal end of the outer member has a cutting edge cooperable with the cutting edge of the inner member to cut the anatomical tissue as the inner member is rotated. The outer and inner members ordinarily have proximal ends adapted for coupling with a powered surgical handpiece used to rotate the inner member relative to and within the outer member. Many tissue cutting instruments provide for aspiration of anatomical debris through the tissue cutting instrument and/or irrigation at the operative or cutting site via an irrigating or flushing fluid supplied along the tissue cutting instrument.
In tissue cutting instruments of the foregoing type, the outer members may be longitudinally or axially straight or may be longitudinally or axially bent, angled or curved. Depending on the location of the cutting site in the patient's body, angled tissue cutting instruments may better facilitate positioning of the outer member distal end at the cutting site while the handpiece remains external to the patient's body so as to provide better access to the cutting site from externally of the patient's body. The bent, angled or curved outer members of angled tissue cutting instruments typically include a proximal length portion extending distally to a bend, angle or curve and a distal length portion extending distally from the bend, angle or curve to the distal end. Where the outer member is longitudinally or axially bent, angled or curved, the inner member is normally provided with a flexible region adjacent the bend, angle or curve in the outer member whereby the inner member conforms to the longitudinally or axially bent, angled or curved configuration of the outer member while still being rotatable within the outer member. Angled tissue cutting instruments of the latter type are represented by U.S. Pat. No. 177,490 to Fones, U.S. Pat. No. 4,445,509 to Auth, U.S. Pat. No. 4,466,429 to Loscher, U.S. Pat. No. 4,646,738 to Trott, U.S. Pat. No. 5,152,744 and U.S. Pat. No. 5,322,505 to Krause et al, U.S. Pat. No. 5,286,253, U.S. Pat. No. 5,411,514 and U.S. Pat. No. 5,601,586 to Fucci et al, U.S. Pat. No. 5,437,630 to Daniel et al, U.S. Pat. No. 5,529,580 to Kusumoki et al, U.S. Pat. No. 5,620,415 to Lucy et al, U.S. Pat. No. 5,620,447 to Smith et al, and U.S. Pat. No. 5,922,003 to Anctil et al.
In most angled tissue cutting instruments, the bend, curve or angle is formed in an elongate body of the outer member as part of the manufacturing or fabrication process and is essentially rigid or fixed. The distal end of the outer member is also ordinarily fixed to the elongate body such that the position of the cutting window relative to the bend, curve or angle is fixed and cannot be varied or adjusted. Accordingly, the outer members of angled tissue cutting instruments are normally provided with a cutting window in a fixed rotational position about a central longitudinal axis of the distal end such that the cutting window faces in a fixed, predetermined direction relative to the bend. This situation presents disadvantages where access to an operative or cutting site is best established with the bend extending in a particular direction or orientation but the fixed position of the cutting window relative to the bend in the particular direction or orientation does not face the anatomical tissue intended to be cut with the instrument at the operative site. While it is possible to rotate the entire instrument to enable the cutting window to face the anatomical tissue intended to be cut, the direction or orientation of the bend is necessarily changed thereby and no longer extends in the particular direction or orientation needed to best establish access to the operative site. Use of the instrument with the cutting window facing the anatomical tissue intended to be cut but with the bend extending in a different direction or orientation may be prohibited due to the presence of anatomical structure at risk of being traumatized due to contact with the instrument. Also, rotation of the entire instrument results in the handpiece being correspondingly rotated, such that the handpiece may no longer be oriented for proper grasping and manipulation by the surgeon.
U.S. Pat. No. 5,601,586 and No. 5,411,514 to Fucci et al are representative of variable angle tissue cutting instruments in which a longitudinally straight outer member has a spiral relief cut forming a non-rigid bendable section along which the outer member may be bent axially by a user, and the inner member is flexible to follow the bent configuration of the outer member. By bending the outer member along the bendable section, a cutting window at the distal end of the outer member can be positioned to face in various directions. Directional positioning of the cutting window cannot be accomplished without bending the bendable section and the distal end cannot be rotationally indexed about its central longitudinal axis. The longitudinal profile of the outer member cannot be maintained and still allow variable directional positioning of the cutting window.
U.S. Pat. No. 5,620,447 to Smith et al relates to an angled tissue cutting instrument in which the outer member has a bendable section formed by a spiral relief cut and is also rotatable about its longitudinal axis to position a cutting window at a distal end thereof in various selected angular positions. The entire outer member must be rotated about its axis in order to vary the angular position of the cutting window. Rotation of the outer member is effected at and with respect to a base at a proximal end of the outer member, the bendable section being necessary to transmit this rotational torque to correspondingly rotate the distal end. A rigid intermediate member having a fixed bend is required between the inner member and the bendable section of the outer member. The bendable section and the intermediate member add undesired structural and functional complexity and cost to the instrument. The base at the proximal end of the outer member requires specialized structure precluding the use of a conventional hub at the proximal end of the outer member.
In view of the foregoing deficiencies of the prior art, a need exists for an angled tissue cutting instrument in which the distal end and elongate body of the outer member are rotatable relative to one another to permit selective rotational indexing of the distal end about its central longitudinal axis to variably position the cutting window of the distal end. A need further exists for an angled tissue cutting instrument providing selective directional or angular positioning of the cutting window relative to a bend, angle or curve in the elongate body of the outer member without requiring rotation of the entire outer member and/or rotation of the entire instrument. There is also a need for an angled tissue cutting instrument that permits selective directional or angular positioning of the cutting window relative to a rigid or fixed bend, angle or curve in a one-piece elongate body of the outer member. An additional need prevails for an angled tissue cutting instrument in which the outer member is movable between a longitudinally extended position wherein the distal end and elongate body of the outer member are prevented from rotating relative to one another about a central longitudinal axis of the distal end and a longitudinally retracted position wherein the distal end and elongate body are rotatable relative to each other about the central longitudinal axis to rotationally index the distal end. A still further need exists for an angled tissue cutting instrument in which distal advancement of the inner member in the outer member a full insertion distance locks the cutting window of the outer member in a selected directional position while retraction or withdrawal of the inner member proximally from its full insertion distance unlocks the cutting window for rotational indexing to another selected directional position. There is also a need for an indexing tool for rotationally indexing a distal end of an outer member so that the fingers of a person's hand do not contact the distal end and particularly do not contact sharp cutting edges on and/or exposed from the distal end. Moreover, there is a need for a kit supplying both an angled tissue cutting instrument having a variably positionable cutting window and an indexing tool for variably positioning the cutting window. Another need exists for a method of variably positioning a cutting window at a distal end of an outer member of an angled tissue cutting instrument by rotationally indexing the distal end by rotating it about its central longitudinal axis relative to an elongate body of the outer member, as permitted by relative longitudinal movement between the distal end and elongate body.